Cutting blades for use in mowers and chippers

ABSTRACT

The blade is made of flat stock, is elongated with a series of the teeth formed along one elongated arcuate edge, the tips of the cutting teeth being disposed along a circular arc. The blade is adapted to be inserted within an elongated slit made in the cylindrical wall of the mower rotor with the teeth protruding from the rotor. The leading end of each blade is provided with an inwardly facing step adapted to rest on the cylindrical wall at the corresponding end of the slit. The trailing end of the blade has a notch to receive the rotor wall at the other end of the slit. The blade has a hole to receive a rod, extending within the rotor and carried by the latter to maintain the blade in position. Each blade has a boss protruding from a main face to prevent the blade from slipping within the rotor. The slit faces are inclined with respect to the rotational axis of the rotor, so as to maintain the blade in an inclined position, to more fully expose the successive teeth for better cutting efficiency. The trailing end of the blade is wider than its leading end to prevent an object from directly impacting against the leading end of a downstream blade.

CROSS REFERENCE DATA

The present application is the Continuation in Part U.S. patentapplication Ser. No. 07/214,372, filed July 5, 1988 (U.S. Pat. No.4,887,418 of Dec. 19, 1989) and entitled "Apparatus for mowing, chippingand blowing."

FIELD OF THE INVENTION

The present invention relates to a multi-purpose comminuting apparatusmore particularly adapted for use as a lawn-mower, as a bush-cutter andas a chipper, and which can also be used, when modified, as a snowblowercombined with an ice-chipper.

BACKGROUND OF THE INVENTION

Most conventional lawn-mowers include one or more blades rotatably abouta vertical axis in a downwardly-opening casing. Such conventionallawn-mowers require an important amount of energy to cut a given surfaceof grass of a predetermined height, and the cut grass tends to adhere tothe inner surface of the casing, such that cleaning of the casing isfrequently required. Moreover, such conventional lawn-mowers requirefrequent sharpening of the blades, and the latter can be readily damagedby stones or the like present on the lawn. Conventional lawn-mowerscannot cut small diameter trunks, such as bush, and are ineffective intall grass.

It is known to provide wood chippers used in the wood industries toconvert tree trunks and branches into wood chips. Such wood chippersinclude specially-designed teeth removably fixed at the periphery of arotor. Each tooth, when damaged or when requiring sharpening, must beindividually removed and fixed back to the rotor, a time-consumingoperation.

In the snowblower field, a large screw is often used for engaging andconveying the snow to an ejector impeller, this screw being sometimesprovided at its peripheral edge with permanently-fixed ice-engagingteeth. Such arrangements are not suitable for cutting grass and the likeflexible material.

OBJECTS OF THE INVENTION

The main object of the present invention is to provide a lawn-mowerwhich obviates the above-noted disadvantages of conventional lawn-mowersand, more precisely, which requires much less expense of energy for thesame amount of mowing; which automatically expels the cut grass or othermaterial; which can cut bush as well as grass in a single pass; andwhich can cut tall grass in a single pass.

Another object of the present invention is to provide an apparatus ofthe character described, which can also be used as a chipper of wood,plastics and the like solid material.

Another object of the present invention is to provide a mower of thecharacter described and which can be easily modified to be used as asnowblower with ice-comminuting capability.

Another object of the present invention is to provide a lawn-mower ofthe character described, provided with a casing arranged such that thecut grass, or the like material, can be ejected directly at the back ofthe mower or at the front thereof, depending on the requirements.

Another object of the invention is to provide a lawn-mower of thecharacter described, in which the grass can be cut at an adjustedlength.

Another object of the invention is to provide an apparatus of thecharacter described, in which the cutting blades can be quickly andeasily removed for replacement or sharpening, whenever required.

Another object of the invention is to provide an apparatus of thecharacter described in which the cutting blades are inclined withrespect of the rotor axis so as to better expose the successive cuttingteeth along the blade for more efficient cutting action.

SUMMARY OF THE INVENTION

The apparatus of the invention includes a power operated rotor rotatablymounted for rotation in one direction and having a cylindrical wallprovided with helically-arranged elongated slits, blades removablyinserted in the slits and protruding from said cylindrical wall, theblades each having a series of teeth disposed along a portion of anhelix co-axial with the rotor and fixing means to releasably fix theblades to the rotor. The blades rae flat and elongated and are arrangedin a plane which is inclined with respect to the rotor axis, preferablybetween 8 and 13 degrees and most preferably at 10 degrees. This morefully expose the successive teeth of the blade to the material forbetter cutting efficiency.

Preferably, when the blade and rotor are viewed from the top the bladeinclination is towards the right while the blade extends from right toleft towards the trailing end relative to the rotor rotational axis.

Preferably, each blade is formed with a notch at one end and a radiallyinwardly facing step at the other end.

Preferably, a hole is made in the blade radially inwardly of the notch.Two holes may made the blade adjacent the leading and the trailing endsrespectively. Preferably a boss is made in the blade radially outwardlyof said notch to prevent falling of the blade through a slit within therotor.

Preferably, the portion of the trailing end of the blade which isdisposed radially outwardly of the notch is wider than the portion ofthe leading end of the blade which is disposed outwardly of the step. Inthis manner, the trailing end of the leading blade prevents hard objectsfrom directly hitting the leading end of the trailing blade preventingdamage to the latter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the apparatus used as a lawn-mower andmounted at the front of a motor vehicle;

FIG. 2 is a cross-section of the apparatus of FIG. 1, this cross-sectionbeing taken along line 2--2 of FIG. 4;

FIG. 3 is a longitudinal section, partially broken, and taken along line3--3 of FIG. 2;

FIG. 4 is a rear end elevation, partially broken, and taken along line4--4 of FIG. 2;

FIGS. 5 and 5a are partial cross-sections of a part of FIG. 2 andshowing the deflector plate in open and closed position, respectively;

FIG. 6, shown on the fifth sheet of drawings, is a partial schematicelevation showing one group of slits and blades defining a completespiral around the rotor;

FIG. 7 is a schematic end elevation of the rotor shown in FIG. 6;

FIG. 8 is a partial developed plan view of the arrangement of the slitsat the cylindrical wall of the rotor;

FIG. 9, shown on the fourth sheet of drawings, is a partial longitudinalsection of another manner of mounting the rotor;

FIG. 10 is a partial cross-section of the rotor showing how a blade isinserted in a slit thereof;

FIG. 11 is a longitudinal section of the rotor showing one manner ofmounting the driving motor inside the rotor;

FIG. 12 is a longitudinal section of the rotor showing how it is mountedin the casing when the driving motor is on the outside;

FIG. 13 is a view similar to that of FIG. 11, but showing another mannerof mounting the driving motor inside the rotor;

FIG. 14 is a schematic end view of a rotor used as a chipper;

FIG. 15 is a partial cross-section, similar to FIG. 2, but showing amodified blade, the teeth of which are provided with extensions used asimpellers;

FIG. 16 is a partial side elevation of the modified blade;

FIG. 17 is a cross-section along line 17--17 of FIG. 16;

FIG. 18 is a top plan view taken along line 18 of FIG. 17;

FIG. 19 is a partial side elevation of the modified blade prior tobending of the extensions;

FIG. 20 is a cross-section of the rotor and showing a second embodimentof the blades carried by the rotor;

FIG. 20a is a cross-section of the rotor and showing a third embodimentof the blades carried by the same;

FIG. 21 is a partial longitudinal section of the rotor an inclined endline blade and taken along line 21--21 of FIG. 20a;

FIG. 22 is an enlarged view of the portion delimited by circle 22 ofFIG. 20; and

FIG. 23 is a cross section taken along line 23--23 of FIG. 22.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows the apparatus of the invention, generally indicated at A,used as a lawn-mower and mounted at the front of a vehicle B as by meansof struts 20 pivoted at 22 to the front of the vehicle, and at theirlower end pivoted to brackets 24 extending rearwardly from the casing 26of apparatus A. Struts 20 may be pivotally connected intermediate theirends to a yoke 28 extending across the front of vehicle B and pivoted at30 to the vehicle body. Any other type of mounting the apparatus infront of the vehicle B to be pushed thereby can be provided.

As shown in FIGS. 1 and 2, the casing 26 includes end walls 32 joined bya transverse wall 34 at the top of the casing. A rotor 36 is rotatablymounted within the casing 26. Rotor 36 is journalled in the end walls32. It comprises a cylindrical wall 38 supported at its ends on end caps40. One end cap 40 is keyed at 42 to a shaft 44, which supports androtates the rotor 36. The shaft 44 has at its other end a flange 46which is bolted to the associated end cap 40. Shaft 44 is journalledinto the two end walls 32 of the casing 26 by means of bearings 48. Ahydraulic motor 50 is secured by bolts 52 to one end wall 32 on theoutside thereof and its output shaft is splined within the end of shaft44. Thus, the rotor 36 can be driven in rotation by the hydraulic motor50, which is supplied by hydraulic fluid by a suitable hydraulic pump,not shown, carried by the vehicle B. Obviously, a mechanical drive couldbe derived from the vehicle B to the rotor 36.

The rotor 36, when looked at in FIG. 2, is driven in clockwisedirection.

The cylindrical wall 38 thereof is provided with a plurality of slits54, as shown in FIG. 8. Slits 54 are arranged in sets, preferably threesets, around the rotor. The slits of each set are substantially alignedtransversely of the rotor, with their leading ends 56 disposed along afirst generatrix of the rotor and their trailing ends 58 disposed abouta second generatrix of the cylindrical wall 38. The slits 34 are ofsubstantially equal length, extending through about 40 degrees aroundthe cylindrical wall 38. The slits are equally inclined at about 12degrees with respect to the longitudinal axis of the rotor 36. There arethree sets of slits 54, equally angularly spaced around the rotor. Withthis arrangement, the intervening portion of the cylindrical wall 38between each set of slits is sufficiently wide to provide slits in eachset to provide a nine-entry arrangement, as indicated by numbers 1 to 9repeating themselves just above the horizontal line Ca in FIG. 8. Thearrangement is preferably such that, as shown in FIG. 6, any selectedslits of the three sets form a complex helix in alignment around thecylindrical wall. The slits are also so arranged that referring to FIG.8, and more particularly as indicated by the vertical line 60, theleading ends 56 of the slits 54 of a given set overlap in the rotationaldirection of the rotor the trailing ends 58 of the slits of a leadingset.

A blade, or rasp 62, is removably inserted and retained in each slit 54.Each rasp 62 is of similar size and shape, as more particularly shown inFIG. 2. The rasps 62 in FIG. 2 are indicated as A, B, and C,corresponding to the same arrangement as shown in FIG. 6, so as to forma complete spiral around the rotor. Each rasp 62 is formed of flatstock; is longitudinally straight, of elongated shape. Each rasp 62 hasa notch 64 at its trailing end and an inwardly-facing step 66 at itsleading end. It is a simple matter to insert a rasp 62 within any givenslit 54, as shown in FIG. 10, by holding the rasp and inserting thetrailing end of the rasp within the slit and in such a way that thenotch 64 fits around the portion of the wall 38 defining the trailingend 58 of the slit 54. Then the step 66 is made to abut the outersurface of the cylindrical wall 38 at the leading end 56 of the slit 54.In operative position, the rasp partially protrudes inside the rotor andalso outside of the rotor. It is releasably retained in operativeposition by means of a transverse rod 68 extending through aligned holes70 of the rasps 62 inserted in one set of slits 54 and through alignedholes 72 made in the end caps 40. In this manner, the rasps arepositively retained against centrifugal force, it being realized thatthe rotor, of about one and a half foot in diameter, is designed torotate at about between 1800 and 2000 r.p.m.

The retaining rods 68, as shown in FIG. 3, are also used to retain inposition the assembly of the end caps 40 and the cylindrical wall 38when the end caps are removable from the cylindrical wall. In this case,the rods 68 have a threaded end 74 screwed within one end cap and anut-shaped head 76 at the other end.

The rods 68 are angularly, equally spaced around the rotor and are atthe same radial distance from the rotor axis. Each rasp 62 is providedwith outwardly-projecting teeth 78. Each tooth 78 has a tip 80 fromwhich inwardly extends a straight cutting edge 82 which is inclined atabout 80 degrees with respect to the center of rotation of the rotor inthe direction of rotor rotation. Each tooth has a trailing inclined edge84 which is substantially straight and is such that a straight lineextended therefrom will meet the cutting edge 82 of the next trailingtooth 78 above the trough 86 between two teeth 78. With thisarrangement, it has been found that the rotor teeth do not becomeclogged with cut grass, and rotation of the rotor will forcibly ejectthe cut grass in the direction of rotor rotation.

Referring to FIGS. 2 and 3, it is seen that casing 26 maintains therotor at a certain distance above ground G. The end walls 32 have afront portion which is generally circular and co-axial with the rotoraxis and which protrudes radially outwardly from the tips 80 of theteeth 78. These tips 80 are all disposed at an equal radial distancefrom the rotor axis, and when rotating, come in sliding contact with aplate shoe 88 disposed substantially parallel to the rotor axis andtangent to the tooth tips 80.

The plate shoe can be made of a plastic material and is supported by atransverse support plate 90 extending between the two ends walls 32 andfixed to end levers 92 pivoted to the end walls at 94. Preferably, theend levers 92 are adjustably fixed by bolt 96 extending through a slot98 of the end levers; but the levers can be simple brackets permanentlyfixed to the end walls of the casing. Thus, grass or any other materialto be cut, and which abuts the plate shoe 88 during forward movement ofthe apparatus, will be engaged by the rotating teeth in a scissorlikeaction.

The end walls 32 form a rearward extension, and together with a rearextension of the transverse wall 34, form a rearwardly-directed duct100, which is open at its rear end, as shown at 102, for the rearwardejection through opening 102 of the material cut by the rotor teeth.

The transverse wall 34 extends spacedly over the rotor and define afront edge 104 which is about diametrically opposite to plate shoe 88.Along this front edge 104, is pivotally mounted a cover 106 which iscurved to conform to the front portion of the end walls and which ispivotable between a closed position, shown in FIG. 2 in full line, inwhich the front portion of the casing is only partially open to receivegrass or the like to be cut, and an open position, partially shown indotted line in FIG. 2, to gain access to the rotor and to the rasps 62for ease of maintaining said rasps either for sharpening of their teethor complete replacement of one or more rasps.

The cover 106 is resiliently retained at each end in either one ofclosed or open position by means of a tension spring 108 arranged intoggle-like fashion and attached to the casing at one end and to thecover at the other end.

A partition, made of two sections, transversely extends between the twoends 32 and are fixed to said end walls at the rear of the rotor. Thispartition comprises an upper section 110, in the form of a flat plate,and a lower section 112 which forms a continuation of the support plate90 for the plate shoe 88. The partition 110, 112 defines betweenthemselves an aperture 114 which is closable by a deflector plate 116pivoted at 118 along the lower edge of the upper portion section 110. Toeach end of the pivot shaft of the deflector plate 116 is secured atlever 120 (see FIGS. 5 and 5a) to which is attached a toggle spring 122,the other end of the tension spring being attached to an end wall 34.Thus, the two tension springs 122 resiliently maintains the deflectorplate 116 in open or closed position. In open position, aperture 114allows direct ejection of the material through the duct 100 and thenthrough opening 102 to the outside of the casing. In the closed positionof the deflector plate 116, as shown in FIG. 5a, there is formed acontinuous passage between the rotor and the partitions 110 and 112 anddeflector plate 116, which starts at the shoe 88 and extends around therotor to open at the front end of the closed cover, so that the materialmay be discharged ahead of the apparatus and recuperated in a baginstalled in front of the mower.

The level of the rotor above ground can be adjusted so as to cut thegrass to the required length. For this purpose, a roller 124 extendstransversely of the casing behind the rotor and below the same, beingjournalled at its two ends to levers 126. Each lever 126 is pivotedintermediate its ends at 128 to an end wall 32 just inside the same, andthe rear end of lever 126 is attached by means of a flexible link, suchas a bicycle chain 130, to the lower end of a plunger 134, which isguided for up-and-down movement in a sleeve 136 fixed in uprightposition in the casing, and more particularly through a transversereinforcing tube 138 fixed to the end walls.

Plunger 134 is rotatably attached to a screw 140, which is screwedwithin a nut 142 fixed to the top end of the sleeve 136. Rotation of thescrew 140, by means for instance of handle 144, will adjust the level ofthe plunger 134 and, consequently, the level of the roller 124 withrespect to the rotor 36. The two handles 144 are rotated to the sameextent, so as to ensure that the casing be transversely levelled withrespect to the ground. As an alternate manner, the two hubs 148 of thehandles on said sprockets, so that rotation of one or the other of thehandles 144 will displace the two plungers 134 to the same extent up ordown. In order to maintain the link 130 in taut condition, a tensionspring 150 is connected to each lever 126 intermediate the roller 124and the pivot 128 and is also connected at its top end to thereinforcing tube 138.

FIG. 3 shows an arrangement where both ends of the rotor are driven by ahydraulic motor 50, the latter being mounted on the outside of thecasing. FIGS. 11, 12, and 13 show alternate arrangements in which therotor is driven from only end and in which the driving hydraulic motormay be mounted directly within the rotor.

Referring to FIG. 11, the hydraulic motor 50A is fixed by bolts 52 to anend wall 32 inside the casing and extends within the rotor, one end capof which being modified, as shown at 40A, to provide a sufficientopening for insertion of the motor 50A, the end cap rotatably journalledon the rotor by a large diameter ball bearing arrangement 154. Theoutput shaft 156 of the motor 58A is removably splined into an end of ashaft 158, which has a collar 160 removably bolted to the other end cap40B. The shaft 158 is journalled in a bearing 162 carried by a plug 164secured within a hole made in the other end wall 32 of the casing bybolts 166. By unbolting motor 50A and unscrewing its hydraulic hoses168, and also be removing the plug 164, the assembly of the motor androtor can be easily extracted from the front end of the casing. Themotor is protected against damage and does not form a protuberanceexternally of the casing.

FIG. 13 shows an alternate arrangement wherein one end cap 40C forms adeep recess 170, in which the internally-mounted hydraulic motor 50A isfreely inserted, the output shaft of said motor being directly keyed ina hole in the bottom of recess 170. This figure also shows that the endcaps are provided with an inwardly-facing step 172 at their periphery,overlapping the end of the cylindrical wall 38 of the rotor to preventdisengagement under centrifugal force, if found necessary.

FIG. 12 shows another embodiment in which the rotor is driven from oneend with the driving motor or gear at the outside of the casing 26. Thearrangement is very similar to that of FIG. 13 as far as the right-handside of the rotor is concerned; but the end cap on the left-hand side ismodified so as to secure the drive shaft 174 to the end cap by bolts176.

It has been found that the apparatus just described, when used as alawn-mower to cut grass, will expand about 40% of the energy required byconventional lawn-mowers with blades rotatable about a vertical shaft,cutting grass of the same height and at about the same width of cut.

It has been found that the grass is constantly ejected clear of thecasing, either through its front opening or its rear opening, dependingon the position of the deflector plate. The inside the casing and theteeth of the rasps never becomes clogged. Also high grass can be cut ina single pass. Also, whenever the rotor encounters small-diameter bush,it will chip the bush clean into wood chips.

The rasp teeth normally simply ride over rocks or pebbles lying in thegrass and will not become damaged by the same.

Referring to FIGS. 15 to 19, the rasps 62 may be modified, as shown at62A, with the steel of each tooth 78 being only partially punched outand remaining attached to the tooth at the otherwise cutting edge toform a part 178, 179 which is then bent at right angles to the raspsuccessively in opposite directions, so as to act as a snow impeller.The top outward edge of the bent part 178, 179 will not extend to thetip 80 of the tooth, so that the latter will be able to engage and cutice, which will be comminuted, and the ice and snow thrown out of thecasing by the impellers 178, 179. Impellers 178, 179 may extend on onlyone side of the blade and/or be formed at only every third tooth, if sodesired.

It is to be noted that, because the rasps 62 can be easily removed andreplaced, it is a simple matter to have rasps of different kinds, thatis with different types of teeth, even carbide teeth, to adapt the rotorto various kinds of works, such as wood chipping, and chipping of othertypes of materials including plastic.

The rotor can be mounted, as shown in FIG. 14, with material M to bechipped located on a table 182 transversely disposed along a radius ofthe rotor and having a front edge 184 disposed parallel to therotational axis of the rotor and close to the tip 80 of the teeth.Material M is pushed over the teeth to be comminuted by means of apusher 186. Thus, it is apparent that the rotor assembly, including therasps 62, can be put to different uses for cutting or comminutingdifferent types of material.

Referring to FIG. 20, rotor 36a consists of a cylindrical wall 38amounted on end caps 40a keyed to a drive shaft 44a, as in the firstembodiment. One end cap carries a flange 46a also secured to the shaftby bolts 47a. The cylindrical wall 38a has a plurality of helicallydisposed slits 54a, each receiving a rasp or blade 62a, the rotor 46a isdriven into the rotational direction indicated by arrow 190.

Each blade 62a is made of flat stock, is elongated and one longitudinaledge portion forms a series of teeth of 78a.

The leading end of each blade is formed with a notch 64a, for receivingthe exposed portion of the cylindrical wall 38a at the trailing end ofthe slit 54a.

The leading end of the blade forms a radially inwardly facing step 66ato rest against the wall 38a at the other end of the slit. Each bladehas, near its leading end, a hole for receiving a retaining rod 68alocated within the rotor. The hole is located inwardly of the step 66a.The bore 72a of one end cap 40a receives the end of rod 68a providedwith head 76a, while the other end of rod 68a is threaded to be screwedwithin the opposite end cap 40a as in the first embodiment.

The teeth 78a have tips 80a, disposed in an envelope which is outwardlyspaced from wall 38a and is coaxial with the rotational axis of therotor. Each tooth has a forwardly facing straight cutting edge 82a and atrailing inclined edge 84a, the orientation of which with respect of thetrough 86a is as defined in the first embodiment. If desired, but notessential, each blade can be provided with two holes, each one near endof the blade and each receiving a rod 68a as shown in FIG. 20. Thisconstitutes an additional safety to prevent blade ejection bycentrifugal force in the event of blade breakage.

Each blade has a leading end 192 and a trailing end 194. The outer edgeportion 196 of the trailing end 194, immediately outwardly of notch 64a,is outwardly spaced from wall 38a, a greater distance than the outeredge portion 198 outwardly of step 66a at the leading end 192 of theblade 62a.

With this arrangement shown in FIG. 20, having regards to the directionof the rotation 190 of the rotor, it will be appreciated that any hardobject will be prevented from directly hitting the leading end 192 of ablade by the trailing end 194 of the upstream for leading blade. Damageto the leading end of the blades is prevented.

FIG. 20a shows a blade 63a having all the characteristics of blade 62aexcept that the trailing portion of the blade is formed with additionalteeth 202, for more efficient cutting of the material.

During assembly of the blades with the rotor, it might happen that theblades will sip within the rotor through the slits. In order to preventthis, a boss 206 is punched within the blades 62a or 63a to protrudefrom one main face of the blade.

Boss 206 is disposed on the radially outer portion of the blade near theteeth and preferably at the trailing end of the blade.

In accordance with another improvement, it has been found that laterallyinclining the blades with respect to the rotational axis of the rotor asshown in FIG. 21, the spacing of the successive cutting teeth of theblade in the direction of the rotor axis is still increased relative tothe spacing obtained by the sole helical positioning of the blade. Thelateral inclination is defined by angle α from line 208 normal to therotor axis. The preferred range of inclination is between 8 and 13degrees, the preferred angle is 10 degrees. This is obtained simply byslanting the side walls of slit 54a at the required inclination.

The direction of the inclination is such that, when the blade and rotorare viewed from the top, the inclination will be towards the right whilethe blade extends from right to left towards its trailing end relativeto the rotor rotational axis.

I claim:
 1. An apparatus for use as a mower or chipper comprising asupport, a power driven rotor rotatably mounted on said support forrotation in one direction, said rotor having a cylindrical wall providedwith helically arranged, elongated slits, flat blades removably insertedin said slits and protruding from said cylindrical wall, each bladehaving a series of teeth disposed along a portion of a helix coaxialwith said rotor and means to fix said blades to said rotor in a radiallyinclined position relative to the rotor rotational axis.
 2. An apparatusas defined in claim 1, wherein said inclination is between eight andthirteen degrees.
 3. An apparatus as defined in claim 1, wherein saidinclination is about 10 degrees.
 4. An apparatus as defined in claim 1,wherein said rotor and any blade are seen from the top, said inclinationis towards the right while the blade extends from the right to lefttowards its trailing end relative to the rotor rotational axis.